Impedance spectroscopy study of Al/p-Cu2ZnSnS4 thin films Schottky diode grown by a two-stage method

In this paper, we report the electrical properties of Al/p-Cu2ZnSnS4 thin film Schottky diode fabricated by a two-step method. Cu2ZnSnS4 ingot was successfully grown by direct melting of the constituent elements, then (CZTS) thin film was grown using thermal evaporation method onto heated Mo substrate temperature at 100 degree celsius. After that, the as-deposited CZTS sample were annealed in a sulfur atmosphere at 400 degree celsius for 30 min. X-ray diffraction analysis reveals a polycrystalline CZTS preferentially oriented along a (112) plane in kesterite structure. For bulk material, the band gap energy is about 1.39 eV, the complex impedance plots display a semicircle with an equivalent circuit consisting of a parallel RC circuit connected to a series resistor. The CZTS thin film was investigated in the way of structural and electrical properties. Raman spectra ensured formation of kesterite CZTS phase. Dense and polycrystalline surface features were observed in SEM images of CZTS thin film. The I-V characteristics showed that a Schottky contact was obtained between Aluminum and p-Cu2ZnSnS4 absorber layer. Characteristic parameters such as saturation current, ideality factor and series resistance were calculated from the experimental I-V data. These parameters showed significant electrical properties such as low series resistance and an ideality factor between 1 and 2. Finally, the Arrhenius diagram provided a very low activation energy of about 2.03 meV.